A144239 - OEIS

A144239

Number of n X n binary arrays, symmetric about main diagonal, with every 1 adjacent to at least one other 1 both bishopwise and rookwise but with no three 1s in a row bishopwise or rookwise.

%I #3 Mar 31 2012 12:35:07

%S 1,2,3,9,28,108,984,7649,73052,1440611,30613610,770498233,33712608974,

%T 1836317274474,122794791129401,12495584324152671,1697400189654813806

%N Number of n X n binary arrays, symmetric about main diagonal, with every 1 adjacent to at least one other 1 both bishopwise and rookwise but with no three 1s in a row bishopwise or rookwise.

%K nonn

%O 1,2

%A _R. H. Hardin_, Sep 15 2008